Spinal implant systems provide a rod for supporting the spine and for properly positioning components of the spine for various treatment purposes. Bolts, screws, and hooks are typically secured to the vertebrae for connection to the supporting rod. These vertebral anchors must frequently be positioned at various angles due the anatomical structure of the patient, the physiological problem being treated, and the preference of the physician. It is difficult to provide secure connections between the spinal support rod and these vertebral anchors at all the various angles and elevations that are required, especially where there are different distances between the rod and bolts and where these components are located at different heights on the patient.
What is needed is a connection assembly between a spinal rod and a vertebral anchor that allows the surgeon to fix the desired elevation between a rod and the bone anchor as well as fix the desired angle between the anchor and rod. The following invention is one solution to that need.
In one aspect, this invention is a connection assembly between a spinal implant rod and a vertebral anchor. The connection assembly has a spindle. The spindle has an aperture for receiving a portion of a spinal implant rod and a compression member forceably, for example threadably, engageable into the spindle to urge a spinal implant rod against the internal walls of the aperture. The connection assembly also has housing, for example a spindle block. The housing has an aperture for receiving a portion that projects from the spindle and an aperture for receiving a portion of a vertebral anchor, the aperture for the spindle also being open to the aperture for the vertebral anchor. A second compression member is then forceably engaged into the housing to urge the spindle against the vertebral anchor (or the vertebral anchor against the spindle), securing the housing to the vertebral anchor and the spindle.
In another aspect this invention is a connection assembly between a spinal implant rod and a vertebral anchor. This connection assembly also has spindle and compression member as previous described. This embodiment uses a means for connecting the vertebral anchor to the spindle at a variable angle.